line drawing bug

form := Form extent: 100@100 depth: 32.

form fillWhite.

canvas := BalloonCanvas on: form.

canvas aaLevel: 4.

"canvas := FormCanvas on: form."

points := { {10@10 . 50@43} . {50@42 . 90@75} . {90@75 . 50@90 } }.

points do: [ :p |

   canvas drawPolygon: p

      color: Color transparent

      borderWidth: 1

      borderColor: Color red.

   canvas drawString: p first asString

      at: p first

      font: nil

      color: Color green.

].

morph := ImageMorph new.

morph image: form.

morph openCenteredInWorld.

hi,

real question is why you use Balloon and not Athens :)

cheers,
Esteban

Does { jb } want to deploy on tablet computer (Android or iOS) ?


Le <a dir="ltr" href="tel:06/04/2018" x-apple-data-detectors="true" x-apple-data-detectors-type="telephone" x-apple-data-detectors-result="1">06/04/2018 à 12:31, Esteban Lorenzano a écrit :

real question is why you use Balloon and not Athens:)

--
Dr. Geo
http://drgeo.eu

Hi Joe,

the problem is that the BalloonCanvas (or some objects it is using) aren't fully reset after some drawing operations.

(the drawString method for example sets the sourceForm as glyph to be drawn).

it should work if you do not store the canvas instance, but create a new in every loop:

    points do: [ :p |

       canvas := form getCanvas asBalloonCanvas aaLevel:4; yourself.

       canvas drawPolygon: p
          color: Color transparent
          borderWidth: 1
          borderColor: Color red.

       canvas drawString: p first asString
          at: p first
          font: nil
          color: Color green.
    ].

Or just reset the engine state (but I don't like this solution, the engine state should be private to the canvas).

    points do: [ :p |
   
       canvas drawPolygon: p
          color: Color transparent
          borderWidth: 1
          borderColor: Color red.

       canvas drawString: p first asString
          at: p first
          font: nil
          color: Color green.
       canvas resetEngine.
    ].

2018-04-06 2:57 GMT+02:00 <[hidden email]>:

Hello everyone!

Im trying use the balloon canvas to draw some nice smooth anti aliased lines, but now i seem to have hit upon a bug which i dont know how to fix.

if i draw just lines i get everything i want.  but if i add a “drawString:…” in there at any point, all the lines i try to draw subsequently dont show up.

Here is code that shows the exact issue:

form := Form extent: 100@100 depth: 32.

form fillWhite.

canvas := BalloonCanvas on: form.

canvas aaLevel: 4.

"canvas := FormCanvas on: form."

points := { {10@10 . 50@43} . {50@42 . 90@75} . {90@75 . 50@90 } }.

points do: [ :p |

   canvas drawPolygon: p

      color: Color transparent

      borderWidth: 1

      borderColor: Color red.

   canvas drawString: p first asString

      at: p first

      font: nil

      color: Color green.

].

morph := ImageMorph new.

morph image: form.

morph openCenteredInWorld.

if i comment out the canvas drawstring i get what you would expect: a squiggly line.  

if i add in the drawstring, the first line shows up but all the subsequent lines do not get drawn.  (both images attached)

I spent a bunch of time tracking it down to its most purest form and then a bunch of time debugging it and im out of my depth with the baloon code, i cant seem to figure out whats wrong.  if anyone knows whats wrong or can give me a clue on how to fix it i’d greatly appreciate it.

thanks in advance.

{ jb }